1. Field of the Invention
The present invention relates to a data recording medium for recording data as an optically readable code and a code reader for reading that code from the data recording medium.
2. Description of the Related Art
Conventionally, a variety of computer processable information such as voice, image, text, etc. is recorded on a medium, such as paper, in the form of optically readable codes, such as one- or two-dimensional barcodes. This technology is described in U.S. Pat. Nos. 5,896,403, 5,866,895, etc.
FIG. 1 shows a physical format configuration for a dot code disclosed in these publications.
This dot code 1 comprises a plurality of blocks adjacently arranged in a two-dimensional manner. Each block 2 contains a data area 3 in which black and white dot images are provided in a specified two-dimensional array. Data including voice etc., to be recorded is divided into blocks, each of which is represented as a black dot or a white dot corresponding to values xe2x80x9c1xe2x80x9d or xe2x80x9c0xe2x80x9d of a block of data. It should be noted that a white dot in FIG. 1 is equivalent to the color of the recording medium itself. Further, each block 2 includes a marker area, a pattern dot 6, and a block address pattern (block ID area) 7. The marker area contains a marker 5 which comprises a specified number of sequential black dots and is placed at the four corners of each block used for finding a reading reference point to read each dot (data dot 4) in the data area 3. The pattern dot 6 is a set of independent dots placed between markers 5 and is used for more accurately finding the reading reference point. The block address pattern 7 contains an error detection or correction code and is also placed between markers 5 for identifying each block 2. The marker 5 and the pattern dot 6 are surrounded by a completely white no-dot area 8 for easily detecting them.
There may be a case where the whole dot code 1 is larger than the visual field 9 of the reader, in other words, the dot code 1 cannot be picked up with a one-shot operation. Even in this case, the dot code 1 makes it possible to reconstruct the whole original data by collecting data contained in each block 2. For this purpose, an address given to each block 2 should be detected together with data dots 4 contained in the block on a block basis. This also enables recording of large amounts of data, such as voice, on the paper and easily reading that data by manual scanning.
For example, Jpn. Pat. Appln. KOKAI Publication Nos. 11-039417, 11-039418, etc. disclose a reader for reading such an optically readable code as the dot code 1 from a recording medium which records that code. According to this reader, the above-mentioned code is recorded along a specified side of a recording medium. This side thereof is touched to a slit-shaped guide groove. The code is read by manually moving the recording medium in the groove along that side.
In the reader that reads the code by manually scanning the recording medium whose specified side touches the slit-shaped guide groove, the recording position of the code on the recording medium along that specified side itself is defined on the basis of that specified side. An image pickup section is arranged so as to provide an image pickup area corresponding to that specified position. In this case, the image pickup area is designed to be larger than the code width so that the code can be read reliably. This aims at offsetting a recording position error for the code or a blur during the manual scanning. When the image pickup area is configured to be larger than the code width, however, the reader may incorrectly recognize an image other than the code (hereafter referred to as a peripheral image) captured in the image pickup area. As a countermeasure against this peripheral image, a possible solution may be to arrange the code sufficiently far from the peripheral image. This can prevent a block containing effective data and the peripheral image from being picked up simultaneously, and eliminate data read errors caused by these peripheral images.
However, a recording surface cannot be used effectively simply by arranging the code far from the peripheral image so that they are not picked up simultaneously. For example, recording a single code requires a large amount of space around that code. This degrades the recording density and greatly restricts the recording surface layout.
Even if the image pickup area contains only the code, an actually picked up image incorporates many redundant elements other than the code when the code is detected from that image. It would therefore take a long time to detect the code, delaying the code-reading operation.
The above-mentioned problems occur not only in manual scanning of a recording medium, but also in mechanical scanning. Further, the same problems also concern a pen-type reader as disclosed in, e.g., U.S. Pat. No. 6,170,750 B1 and Jpn. Pat. Appln. KOKAI Publication No. 11-334253. This pen-type reader is used for manual scanning of codes on a recording medium by placing the reader on a guide.
The present invention has been made in consideration of the foregoing. It is therefore an object of the present invention to provide a data recording medium and a code reader capable of decreasing restrictions on the layout, effectively using the recording surface, and speeding up the read operation.
According to a first aspect of the present invention, there is provided a code reader to read a code from a data recording medium which records data as an optically readable code and is provided with a non-interference area around the code to prevent presence of only an interference image having an attribute causing an error during reading of the code, the code reader comprising:
an image pickup section to pick up the code;
a guide section configured to specify positional relationship between the image pickup section and the code;
a code detection section to set a code detection area in an image pickup screen obtained in the image pickup section and detect at least part of the code from the inside thereof; and
a restoration section to specify the code from the image pickup screen based on a detection position of at least part of the code detected in the code detection section and restore data recorded in the code, wherein
the code detection area is determined based on an alignment error between the image pickup section and the code due to the guide section and a specification of the code.
According to a second aspect of the present invention, there is provided a code reader to read the code from a data recording medium which records data as an optically readable code, comprising:
an image pickup section to pick up a code;
an image detection section to detect a specified image from an image pickup screen obtained in the image pickup section, the specified image being provided near the code on a data recording medium and being positioned according to a specified positional relationship with the code; and
a restoration section to specify the code from the image pickup screen based on a detection position of the specified image detected in the image detection section and to restore data recorded in the code.
According to a third aspect of the present invention, there is provided a data recording medium comprising:
a portion where data is recorded as an optically readable code; and
a non-interference area which is provided around the code and prevents presence of only an interference image having an attribute causing an error during reading of the code, wherein
the recording medium stores the code read by a code reader having an image pickup section to pick up a code, a code detection section to set a code detection area in an image pickup screen obtained in the image pickup section and detect part of the code from the inside thereof, a restoration section to specify the code from the image pickup screen based on a detection position of part of the code detected in the code detection section and restore data recorded in the code, and a guide section configured to specify positional relationship between the image pickup section and the code, and
the non-interference area is determined based on the code detection area, an alignment error between the image pickup section and the code due to the guide section, and a specification of the code.
According to a fourth aspect of the present invention, there is provided a data recording medium comprising:
a portion where data is recorded as an optically readable code; and
the other portion, wherein
the recording medium stores the code read by a code reader having an image pickup section to pick up a code, an image detection section to detect a specified image from an image pickup screen obtained in the image pickup section, and a restoration section to specify the code from the image pickup screen based on a detection position of the specified image detected in the image detection section and to restore data recorded in the code, and
the specified image is provided near the code on a data recording medium and is positioned according to a specified positional relationship with the code.
According to a fifth aspect of the present invention, there is provided a card-shaped data recording medium comprising:
a portion which records visually readable images such as a character, symbol, figure, pattern, photo, etc.; and
a portion which records data as an optically readable code along a given cut side, wherein
a non-interference area is provided around the code to inhibit presence of only an interference image, out of the visually readable images, having an attribute causing an error during reading of the code, and
the non-interference area contains a longer width between the code and the cut side than a width between the code and the visually readable image arranged adjacently to the code.
Additional objects and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objects and advantages of the invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out hereinafter.